Missile guidance system



Aug. 25, 1964 E. Q. SMITH, JR

MISSILE GUIDANCE SYSTEM 2 Sheets-Sheet 1 Filed June 27, 1957 -Vl- Tolst. Ajrfojl Relay -V2- To zndAgrlogl Relay 'V3" To 3rd. Agrioql Relay-V4- To 4th Alrfoll Relay ELECTRONIC GUIDANCE Fig Fig.2

AorA'= Location of Ist. Airfoil Relay BorB'= Location of 2nd.AirfoilRelay CorC'= Location of 3rd.Airfoi| Relay DorD'= Location of4th.Airfoil Relay INVENTOR. E.QU|MBY SMITH JR.

0 ATTORNEYS Aug. 25, 1964 E. Q. SMITH, JR 3,145,949

MISSILE GUIDANCE SYSTEM Filed June 27, 1957 2 Sheets-Sheet 2 Fig. 5

To Control Circuit of Fig. l

ToControl 56 Cjrcui'r of fl Fl 9. I

. INVENTOR.

E. QUIMBY SMITH JR.

3,l45,94 Patented Aug. 25, 1964 3,145,949 MTSSTLE GUIDANCE SYSTEM E.Quimhy Smith, lira, 714 Roderick St, fixnard, Calif. Filed June 27,1957, Ser. No. 668,574 9 Claims. (Cl. 244-14) (Granted under Title 35,US. (lode (1%2), sec. 266) The invention described herein may bemanufactured and used by or for the Government of the United States ofAmerica for governmental purposes without the payment of any royaltiesthereon or therefor.

The present invention relates to missiles or projectiles incorporatingsome form of target-seeking, or homing, apparatus responsive to thereception of radiant energy emanating from the target itself, suchapparatus operating to control the course of the missile in response tovariations in the characteristics of the radiant energy received.

This application constitutes a further development of the concept setforth in application Serial No. 668,576, filed jointly by the presentapplicant and Willy A. Fiedler on June 27, 1957, now Patent No.3,014,426.

In application Serial No. 668,576 there is disclosed a dual purpose airdiffuser for jet engines having an annular air intake duct, or port,made up of an essentially tubular casing surrounding a central needleportion, or spike. The inner surface of this casing, as well as theouter surface of the spike, are configured for high aerodynamicefliciency as an air compressor, while at the same time acting (in onepreferred embodiment) to sequentially reflect radiant energy raysemanating from the target to a common collection region located withinthe body of the missile. As an example, one surface of the diffuser unitmay be of essentially elliptical form, while the remaining surface maydefine an inverted paraboloid of revolution.

Expressed differently, the invention of the prior joint application isdirection to a combined air diffuser and radiant energy collector formissile engines of the ram-jet type, this unit being so designed thatradiant energy from a target may be sequentially reflected from aplurality of diffuser surfaces and then brought to an approximate focalpoint on or near the missile axis.

That portion of the above concept which relates to the collection ofradiant energy by a projectile has proven to be of considerable value ineliminating many of the problems heretofore present in so-called seekersystems. However, the prior invention is restricted to missile designsin which a ram-jet engine is employed, and in which air for the jetengine enter through an annular intake region or port.

It has now been found that the basic optic collection principledisclosed in the mentioned joint application may be adapted to otherforms of projectiles, such for example as missiles which do not requirefor their operation a source of air under compression. In thesecircumstances, it is necessary to provide other means for performing thereflecting function which, in the prior application, is carried out bythe inner surface of the tubular cowling surrounding the inner nose-coneor spike. In other words, it is necessary to again reflect inwardly to acommon focal region those radiant energy rays which have initially beenoutwardly reflected from the surface of the missile nose-cone.

The above objective may be accomplished, in a preferred embodiment ofthe present concept, by providing an aerodynamic direction controlsurface in the form of a rotary-symmetrical air vane, mounted on theforward portion of the projectile body and spaced radially therefrom.The surface of this air vane is adjustable relative to the surface ofthe missile in response to control forces developed as a function ofchanges in the characteristics of the received energy from the target.There is a particular inter-relationship of missile axis, air vaneposition, and target which, when the air vane is in proper alignment,enables the latter to provide a continuously-active aerodynamic force onthe missile in the direction of the target.

The inner surface of the air vane is made of a highly polished material,and is so configured as to direct to a common focal region those radiantenergy rays reflected to it from the outer surface of the missilenose-cone section. Since the air vane is maintained in alignment withthe target by means of the guidance system carried by the missile, itretains a substantially constant angular relationship with the arrivingenergy rays, which results in the latter being directed to a commoncollection region regardless of minor deviations in missile trajectory.

One object of the present invention, therefore, is to provide a radiantenergy collector for projectiles of the seeker or homing class.

Another object of the invention is to provide an assembly fortarget-seeking missiles whereby radiant energy emanating from suchtarget will be sequentially reflected from a plurality of opticallycomplementary surfaces prior to collection and utilization, one of suchsurfaces acting as a missile flight-control member.

A further object of the invention is to provide a radiant energycollection system for seeker missiles in which a high signal-to-noiseratio may be established and maintained.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

FIGS. 1 and 2 are partly schematic side and front views, respectively,of the fore-part of a rocket-type projectile incorporating a preferredform of the present invention, certain portions of the projectile beingshown by cross sections taken along the lines II and II-ll;

FIG. 3 illustrates the operation of the flight control airfoil of FIGS.1 and 2;

FlGS. 4, 5, and 6 are detailed showings of the construction andoperation of certain of the components of FIGS. 1 and 2; and

FIGS. 7 and 8 illustrate one form of aerodynamic control mechanism whichis suitable for use with the projectile of FIGS. 1 and 2.

Referring now to FIGS. 1 and 2, there is illustrated the fore section ofa projectile of the rocket type, this projectile incorporating aradiant-energy collector designed in accordance with the principles ofthe present invention. The projectile includes a body it), of generallycylindrical configuration, having a tapered or pointed nose section 12.The latter defines a surface of revolution relative to the longitudinalaxis 14 of the projectile. Rocket 16 is provided with some suitable formof solid or liquid propellant which is carried in its after section (notshown). However, the details of this portion of the projectile,including the combustion chamber and exhaust nozzle, form no part of thepresent invention, and hence have been omitted from the drawings for thesake of clarity.

A missile on which the apparatus of the present invention is installedis intended to seek out a source of radiant energy. Accordingly, themissile must be able to intercept incident energy from such a target orsource, and to convert variations in this received energy into flightcontrol information.

The above considerations, therefore, dictate a radiant energy collectorwhich is of such dimensions, in aplane normal to the longitudinal axisof the missile, that a sizeable bundle of energy radiations areintercepted and directed to some form of transducer for conversion intocontrol information. In general, the greater the crosssectional area ofthis bundle of rays, the higher will be the signal-to-noise ratio of thedeveloped error voltage.

In the mentioned application Serial No. 668,576 it has been disclosedhow the forward nose section of a projectile can serve as a portion of aradiant energy collection system. In accordance with the arrangementtherein set forth, the incident energy is doubly-reflected, once fromthe forward nose section of the missile to the undersurface of anannular shell or cowl, and thence from the latter to a common focalpoint lying on or near the missile axis. This shell, or cowl, in thementioned application, actually forms the exterior casing or cover ofthe missile, and the spacing between this shell and the inner bodymember constitutes an air compressor unit for the jet engine by whichthe missile is propelled.

Since a rocket motor needs no source of air under compression, a dualpurpose design such as set forth in the mentioned disclosure isinapplicable. However, the advantages of the optic-collection principleper so can be obtained in a manner to be set forth below.

Referring again to FIGS. 1 and 2, the projectile is provided with anannular air vane 16 (also termed a canard) mounted adjacent to, andconcentric with, its forward nose section 12 by means of fourradially-extending support fins 18, 20, 22, and 24 which are rigidlyafiixed to the body of the projectile. The air vane 16 is ofrotary-symmetrical design and preferably of triangular cross-section(FIG. 1), althought his particular cross-sectional contour has beenselected primarily to provide structural rigidity and may be modifiedwithin aerodynamic limits as may be necessary or desirable. It isessential, however, that the inner surface of this air vane 16 be offrusto-conical configuration, and possess satisfactory reflectioncharacteristics for any radiant energy incident thereon. Such a materialas highly-polished stainless steel has been found to be very suitablefor this purpose.

In the mentioned application it has been disclosed that, if radiantenergy rays arriving along parallel paths are sequentially reflectedfrom two surfaces which are chosen to be optically complementary, thenthe reflected energy may be brought to a common focal point. It has beendemonstrated in the mentioned application that if one of these tworeflecting surfaces is of inverted parabolic configuration, theremaining surface may be either conical or ellipsoidal.

The nose section of the missile of FIGS. 1 and 2 possesses such aninverted parabolic surface. Hence, all energy rays 26 which areessentially parallel both to each other and to the projectile axis 14will be reflected from this surface to what would be a virtual focalring encircling the nose member 12 were it not for the presence of theair vane 16. The latter, as previously brought out, possesses a highlyreflective inner surface, which serves to again reflect the rays 26 to acommon focal region 28 lying on or adjacent to missile axis 14. Atransducer 30 located in this focal region intercepts the energy rays26. Variations in the amount of energy received by the transducer as aresult of a departure of the missile axis 14 from parallelism with theenergy rays 26 are utilized by an electronic guidance system 32 tocontrol the flight course of the projectile through the creation of anunbalanced drag force on the airfoil 16 as a result of selectiveactuation of a plurality of electro-magnetic relays. The latter will bemore fully described in connection with FIG. 7 of the drawings.

As in the invention of the mentioned application, an annular portion 34of the wall of projectile 10 lying adjacent to the nose section 12 is soformed ias to permit the passage therethrough of the doubly-reflectedradiant energy rays 26. While this annular section 34 is preferablycomposed of some solid translucent material, it

may in certain cases be merely a ring-shaped air gap of sufiicient widthso as not to cut off any appreciable number of the energy rays reflectedfrom the inner surface of airfoil 16.

In order to establish and/or maintain a flight course for the projectilewhich will bring it to the desired target, guidance system 32 mustoperate to selectively vary the position or alignment of airfoil 16relative to the projectile body. In other words, the airfoil 16constitutes at least a major part of the missiles aerodynamic steeringapparatus. Hence, the latter must be not only mounted for selectivemovement relative to the projectile body, but this relative movementmust be of a universal nature in order to provide omnidirectional flightcontrol.

As stated, the airfoil 16 is of rotary-symmetrical design having aninner surface of frusto-conical configuration. To provide the desiredcontrol, it must be mounted for universal movement about a pivot pointsuch as 36 (FIG. 3) lying on the missile axis 14. As above brought out,the airfoil is coaxially mounted about this axis as part of a unitaryassembly which includes the spike or nose-cone 12. The precise locationof pivot point 36 on axis 14 is determined by the desired aerodynamicrelationship between the missile body and the airfoil 16. It is usuallyselected to minimize drag efifects at high missile speeds.

Referring now to FIG. 3, and assuming that the nature of the energyreceived by transducer 30 is such as to dictate a revision in themissiles trajectory, the position of the airfoil 16 relative to themissile body 10 will be altered in the manner exemplified in thedrawingthat is, it will be moved from one position as shown in solidlines to one such as shown in dotted outline. In other words, theairfoil will be displaced about the pivot point 36 through a certainangle 5. With a universal mounting for the airfoil, this angulardeviation may occur in any quadrant depending upon the phaserelationship of four output voltages V V V and V developed by theguidance system of FIG. 1. Such error-voltage-generating systems andtheir operation are well known in the art to which this inventionpertains.

To permit the airfoil 16 to have such universal freedom of movementthrough a limited range with respect to the body of the missile, theparticular supporting arrangement best shown in FIGS. 2, 4, and 5 may beem ployed. As illustrated in these figures, each of theradially-extending support fins 18, 20, 22, and 24 is diamend-shaped incross-section and is formed such that its furthest surface extremity(indicated by the reference numbers 38, 40, 42, and 44, respectively) isconfigured as a portion of a sphere. These spherically-shaped finextremities are designed to be respectively seated within recesses 46,48, 50, and 52' (of generally rectangular outline but of sphericalcross-sectional configuration) formed in the frusto-conical innersurface of airfoil 16. Since the radius of curvature of both thespherical surfaces 38 through 44 and of the recesses 46 through 52 ischosen with reference to the pivot point 36 (FIG. 3), the airfoil 16will be free to take any angular position (within a limited range set bythe width of the rectangularly-shaped recesses) with respect to axis 14,and the flight of the missile will be governed in accordance therewith.For example, in FIG. 6 the airfoil 16 has as sumed a different angularrelationship with respect to the support fin 24 than is shown in FIGS. 4and 5. It will be noted that the diamond-shaped cross-sectional contourof the fins 18, 20, 22, and 24 prevents an unseating of these fins fromtheir respective recesses 46 through 52, since the sides of each finselectively abut the sides of its associated'recess after a limitedangular movement. This ensures that each support fin will remaindisposed within its respective recess in airfoil 16, while at the sametime permitting sufficient angular movement of these elements to providefor proper guidance of the projectile.

From the above it will be apparent how the airfoil 16 is mounted foruniversal movement relative to the body of missile 10. The instantaneousposition of the airfoil, however, is determined by the characteristicsof the energy intercepted by the transducer 30. The procedure by whichvariations in intensity of the energy received by a projectile developquadrature error voltages is well known to workers in the guided missileart, and since the details of such a system form no part of the presentinvention, the system has been illustrated schematically as one fromfour output voltages V V V and V; are available.

These four error voltages from the guidance system 32 of FIG. 1 arerespectively applied to the windings of four electromagnetic relays, allof which may be similar to the one designated by the reference number 56in FIG. 7. The four relays are located within airfoil 16 andcircumferentialy spaced 90 apart so as to occupy locations such as A, B,C, and D (FIG. 2), or, alternatively, A, B, C, and D. Each relay 56 iselectrically connected to the guidance control system 32 of FIG. 1 bysuitable conductors (not shown) so as to be energized by one of thecontrol voltages V V V and V respectively.

The armature 58 of each relay 56 is elongated and carries a tab 60 onthe extremity thereof opposite to the pivot 61. When the relay isdeenergized, tab 60 lies completely within the airfoil 16, as best shownin FIG. 7. As soon as the relay is energized by an error signal from theguidance system 32, the armature 58 is actuated (upwardly in thedrawing) to raise tab 60 until it extends through an opening 62 in thesurface of the airfoil (FIG. 8). The tab 60, entering the air stream atsubstantially right angles to the surface of the airfoil, creates anaerodynamic drag on that portion of the airfoil with which it isassociated. An unbalanced force created by a selective energization ofless than the total number of relays 56 causes the airfoil 16 to assumea different alignment relative to the body of the missile, and henceresults in a revision of the flight course of the projectile in adirection dictated by the new airfoil position.

Although it might be assumed that any appreciable departure of theincident energy rays 26 from a parallel relationship with the missileaxis 14 might result in a marked reduction in the amount of energycollected by the transducer 30, actual tests indicate that usable errorinformation is available even though the arriving energy rays areconsiderably off-axis. Thus the disclosed system is not likely to permitthe target to be lost, as has occasionally been the case withpreviously-known homing arrangements when the approach angle exceeds apredetermined maximum.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described. For example,the four radially-extending fins 18, 20, 22, and 24 have been describedas being rigidly affixed to the body of the projectile so that theymovably support the air vane 16. If desired, however, the vane 16 may berigidly secured to each of these fins 18-24, and then the latter mountedfor limited universal movement as a unit about a point on the missileaxis 14. This could be accomplished, for example, by a ball-and-socketjoint, one of the elements of which is secured in position relative tothe missile body, and the other element of which carries the foursupport fins so that they extend radially through ap propriately-locatedopenings in the body of the pro jectile.

Iclaim:

1. In a target-seeking projectile assembly adapted to receive energyemanating from the target and to convert such received energy intoinformation by means of which the course of the projectile may becontrolled, said projectile being in the form of an elongated body ofrevolution having a tapered nose-cone section symmetrical with respectto the longitudinal axis of the projectile: the combination Whichcomprises an air vane of essentially rotarysymmetrical configurationacting as an aerodynamic direction control member, said air vane beingspaced radially from, and mounted for universal movement with respectto, that forward portion of said projectile adjacent said nose-conesection, thereby defining an annular air passage between an innersurface of said air vane and an outer surface of the projectile body,the inner surface of said air vane being so configured as to reflect asubstantial proportion of any radiant-energy rays which impinge thereonto a common focal region lying on or near the longitudinal axis of theprojectile; and a radiant-energy-permeable member forming part of thebody of said projectile and lying in the path of those radiant-energyrays which are reflected from the inner surface of said air vane towardsaid focal region.

2. The combibnation of claim 1, further comprising a transducer locatedwithin said projectile body and adapted to convert variations in theradiant-energy rays arriving at said focal region into acorrespondingly-varying electrical characteristic.

3. The combination of claim 2, in which said air vane is mounted forlimited rotary movement about the longitudinal axis of the projectile inresponse to variations in the said electrical characteristic to therebycontrol the course of said projectile.

4. In a target-seeking projectile of the type adapted to utilizeradiant-energy rays emanating from said target for the purpose ofproviding information as to the location of the latter with respect tothe flight course of the projectile, said projectile having at least oneaerodynamic directional control member in the form of arotary-symmetrical vane mounted exteriorly of the body of saidprojectile for universal movement with respect thereto and spacedradially therefrom so as to define an annular air passage therebetween,the inner surface of said vane being of such nature as to reflectradiant-energy rays reaching said surface to a common focal regionwithin the body of said projectile.

5. A projectile according to claim 4, further comprising means forconverting variations in the characteristics of the radiant energyreaching such focal region into information for controlling the flightcourse of said projectile.

6. A projectile according to claim 4 in which said radiant energy raysreach the inner surface of said vane after reflection from the body ofsaid projectile.

7. A projectile according to claim 6, in which that portion of theprojectile body from which said radiant energy rays are reflected is inthe form of an inverted paraboloid of revolution,

8. A projectile according to claim 7, further comprising means forvarying the relative position of said vane with respect to saidprojectile body as a function of variations in the characteristics ofthe radiant-energy rays refleoted by said vane to said common focalregion.

9. A projectile according to claim 8, in which said means for varyingthe relative position of said vane with respect to said projectile bodycomprises means for developing an unbalanced drag force on said vane,the direction and magnitude of such drag force being a function ofvariations in the characteristic of the radiant-energy rays reflected bysaid vane to said common focal region.

Ohlendorf Aug. 12, 1947 Muflly Dec. 28, 1948

4. IN A TARGET-SEEKING PROJECTILE OF THE TYPE ADAPTED TO UTILIZERADIANT-ENERGY RAYS EMANATING FROM SAID TARGET FOR THE PURPOSE OFPROVIDING INFORMATION AS TO THE LOCATION OF THE LATTER WITH RESPECT TOTHE FLIGHT COURSE OF THE PROJECTILE, SAID PROJECTILE HAVING AT LEAST ONEAERODYNAMIC DIRECTIONAL CONTROL MEMBER IN THE FORM OF AROTARY-SYMMETRICAL VANE MOUNTED EXTERIORLY OF THE BODY OF SAIDPROJECTILE FOR UNIVERSAL MOVEMENT WITH RESPECT THERETO AND SPACEDRADIALLY THEREFROM SO AS TO DEFINE AN ANNULAR AIR PASSAGE THEREBETWEEN,THE INNER SURFACE OF SAID VANE BEING OF SUCH NATURE AS TO REFLECTRADIANT-ENERGY RAYS REACHING SAID SURFACE TO A COMMON FOCAL REGIONWITHIN THE BODY OF SAID PROJECTILE.